Thermodynamic analyses and optimization of an auxiliary heat exchanger equipped with an absorption refrigeration system to increase the cooling capability of Heller cooling tower

Abstract

Air-cooled cooling towers are applied to reduce the temperature of water returned from the condenser in the combined cycle power plants. Actually, whenever the ambient temperature increases, the cooling capability of the dry cooling towers decreases and subsequently the performance of the steam turbine Generator (STG) unit of Combined-Cycle Power Plant decreases. To solve this problem, an integrated system including the auxiliary heat exchanger and an absorption refrigeration system is linked to the Heller cooling tower to improve the cooling capability of the cooling tower and subsequently the performance of STG unit. Thus, firstly, the mentioned heat exchanger and the linked absorption refrigeration system have been designed via the validated ASPEN HTFS and Engineering Equation Solver code respectively. Secondly, energetic, exergetic, and exergo-economic analyses of the auxiliary exchanger are conducted. Finally, it is optimized using the Genetic Algorithm. Eventually, the proposed system can help the cooling tower during the hottest times using the wasted heat through the gas stacks. Also, the multi-objective optimization process increases the exergy efficiency from 37.87% up to 39.57% and decreases the total cost rate from 4023.85$/h to 3563$/h.